1. Field of the Invention
The present invention relates to an ink jet recording apparatus for performing recording by ejecting an ink from a recording head to a recording medium.
2. Related Background Art
Recording apparatuses such as a printer, a copying machine, a facsimile apparatus, and the like record an image consisting of a dot pattern on a recording medium such as a paper sheet, a plastic thin plate, or the like on the basis of image information. The recording apparatuses can be classified into an ink jet type, a wire-dot type, a thermal type, a laser beam type, and the like according to their recording methods. Of these recording apparatuses, an ink jet type (ink jet recording apparatus) ejects a flying ink (recording liquid) droplet from an ejection orifice of a recording head, and attaches the ink droplet to a recording medium to record data.
In recent years, a large number of recording apparatuses have been used, and high-speed recording, high resolution, high image quality, and low noise are required of these recording apparatuses. As a recording apparatus which can satisfy such requirements, the ink jet recording apparatus is of note. In the ink jet recording apparatus, since recording is performed by ejecting an ink from a recording head, a printing operation can be performed in a non-contact manner, and a very stable recorded image can be obtained.
Of ink jet recording apparatuses, in an apparatus for ejecting an ink by using a bubble generated by heat energy, the size of a heat generating resistor (heater) arranged in each ejection orifice is remarkably smaller than that of a piezoelectric element used in a conventional apparatus, and a high-density multi-structure of ejection orifices can be realized. A multi head having an array of a large number of ejection orifices is normally time-divisionally driven within a driving period in consideration of the upper limit value of a maximum consumption power allowing simultaneous driving of heaters.
In an ink jet recording method, since an ink as a liquid is handled, various undesirable hydrodynamic phenomena occur when a recording head is used at a speed equal to or higher than or near a critical printing speed. Since an ink is a liquid, the physical states such as the viscosity, surface tension and the like regarding the ink always largely vary depending on the environmental temperature, and the non-use time of the ink. Even when a printing operation can be performed in a given state, it may be disabled due to the environmental temperature or an increase in negative pressure due to a decrease in ink remaining quantity.
Conventionally, when an apparatus is used near a critical ejection period, an ejection error may occur, or the ejection quantity may be extremely decreased. Such situation occurs since refill of an ink to a nozzle (liquid channel) cannot catch up with ejection, and the next ejection is started before the ink is refilled.
In order to cope with this situation, the driving period may be prolonged, i.e., a driving operation may be performed at a period longer than the critical ejection period. However, to prolong the driving period contradicts with the above-mentioned high-speed recording requirement, and cannot be an essential solution.